Relativistic treatment of spin-transfer observables in quasielastic (p,n) scattering

We calculate all spin-transfer observables for the quasielastic (p,n) reaction in a relativistic plane-wave impulse approximation. The nuclear structure information is contained in a large set of nuclear response functions that are computed in nuclear matter using a relativistic random-phase approximation to the Walecka model. A reduced value of the nucleon mass in the medium induces important dynamical changes in the residual isovector interaction relative to its nonrelativistic counterpart. As a result, good agreement is found for all spin observables including the spin-longitudinal to spin-transverse ratio when compared to the original (q=1.72 fm-1) NTOF (neutron time-of-flight facility) experiment. In contrast, the spin-longitudinal to spin-transverse ratio is underpredicted at q=1.2 fm-1 and overpredicted at q=2.5 fm-1. We comment on the role of distortions as a possible solution to this discrepancy.